See discussions, stats, and author profiles for this publication at: http://www.researchgate.net/publication/262004450 The Voltec System: Energy Storage and Electric Propulsion CHAPTER · JANUARY 2014 DOI: 10.1016/B978-0-444-59513-3.00008-X DOWNLOADS VIEWS 960 3,314 2 AUTHORS, INCLUDING: Ulrich Eberle General Motors Company 27 PUBLICATIONS 847 CITATIONS SEE PROFILE Available from: Ulrich Eberle Retrieved on: 08 July 2015 Lithium-Ion Batteries: Advances and Applications edited by G. Pistoia, Elsevier B.V. ISBN 978-0-444-59513-3 http://dx.doi.org/10.1016/B978-0-444-59513-3.00008-X The Voltec System: Energy Storage and Electric Propulsion Roland Matthé, Ulrich Eberle* GENERAL MOTORS EUROPE, ADAM OPEL AG, RÜSSELSHEIM, GERMANY *CORRESPONDING AUTHOR: [email protected]. Abstract: Vehicle electrification is progressing significantly and is changing the architecture of future cars. This trend is a result of the need for higher vehicle efficiency and the desire to diversify the energy sources used for transportation. Voltec vehicles such as Chevrolet Volt and Opel Ampera are electric vehicles (EVs) with extended driving range. They operate as an EV as long as there is useful energy in the battery. However, unlike a pure battery EV, they do not suffer from lost vehicle utility when the battery is depleted. Volt and Ampera can continue operation by using an internal combustion engine as energy converter. Within the framework of this chapter, in addition to the focus on the current Voltec battery and propulsion system technologies, a brief history of the General Motors EV activities is also provided. Keywords: Battery, Chevrolet Volt, Opel Ampera, Propulsion system, Voltec. 8 The Voltec System—Energy Storage and Electric Propulsion Roland Matthé1, Ulrich Eberle2,* 1 GLOBAL BATTERY SYSTEMS, GME ELECTRICAL SYSTEMS, INFOTAINMENT & ELECTRIFICATION, ADAM OPEL AG, RÜSSELSHEIM, HESSE, GERMANY, 2 HYDROGEN & ELECTRIC PROPULSION RESEARCH STRATEGY, GM ALTERNATIVE PROPULSION CENTER, ADAM OPEL AG,RÜSSELSHEIM, HESSE, GERMANY * CORRESPONDING AUTHOR: [email protected] CHAPTER OUTLINE 1. Introduction ................................................................................................................................... 151 2. A Brief History of Electric Vehicles .............................................................................................. 152 3. Extended-Range Electric Vehicles ................................................................................................ 158 4. The Voltec Propulsion System...................................................................................................... 161 5. Voltec Drive Unit and Vehicle Operation Modes....................................................................... 164 5.1. Drive Unit Operation............................................................................................................. 164 5.2. Driver Selectable Modes ....................................................................................................... 165 6. Battery Operation Strategy.......................................................................................................... 165 7. Development and Validation Processes...................................................................................... 169 8. Vehicle Field Experience ............................................................................................................... 171 9. Summary ........................................................................................................................................ 173 Acknowledgments ............................................................................................................................. 174 Nomenclature ..................................................................................................................................... 175 References........................................................................................................................................... 176 1. Introduction Today, the demand for individual mobility is still growing in many parts of the world, particularly in China and India. Temporarily, crude oil prices have already reached values substantially greater than US $100 per barrel, depending on the global market condition and the considered oil grade. In addition, the efforts to reduce greenhouse gas emissions to meet regulatory targets initiated the search for low-carbon fuels and fuels from non-fossil-fuel- based sources. This process accelerated the development of vehicles using electrified Lithium-Ion Batteries: Advances and Applications. http://dx.doi.org/10.1016/B978-0-444-59513-3.00008-X 151 Ó 2014 Elsevier B.V. All rights reserved. 152 LITHIUM-ION BATTERIES: ADVANCES AND APPLICATIONS propulsion systems. After having fallen into oblivion during the first decades of the twentieth century, these technology programs had been restarted in the 1960s, when the development of originally aerospace-related technologies enabled the creation of the world’s first fuel cell electric vehicles (FCEV) and battery electric vehicles (BEV) equipped with high-power bat- teries. During the 1990s, the aim of zero-emission transportation drove the development of electric vehicles (EVs) like the GM EV1 or FCEVs like the various generations of GM HydroGen1 to HydroGen4, as well as the purpose-built GM Sequel. Progress in power electronics, electric motors and the lithium-ion batteries led eventually to cars based on the Voltec system such as the Chevrolet Volt and the Opel Ampera, the first EVs with extended- range (ER) capability in the North American (2010) and European (2011) markets. These vehicles are utilizing a lithium-ion battery allowing 40–80 km of electric range where the electric motors exclusively provide the full power and top speed capability. If the battery reaches a well-defined low state of charge (SOC), a generator driven by an internal com- bustion engine (ICE) starts to provide the required power for long-distance driving. The Voltec vehicles are utilizing an electric air-conditioning and electric cabin heating system. To optimize regenerative braking, the electric drive system can decelerate the vehicle and blend this process with the hydraulic brake system when higher deceleration is demanded. Furthermore, test vehicles equipped with data loggers deliver important data for development, verification and validation on public roads in the United States, Europe and Dubai. Available real-world data confirms how significantly the Voltec propulsion concept can replace gasoline as an energy carrier by electricity. Application of electric energy from renewable sources is reducing the tank-to-wheels (TTW) greenhouse gas emissions further substantially. 2. A Brief History of Electric Vehicles In the late nineteenth and the early twentieth centuries, EVs (see Figure 8.1) played a significant role in the emerging automotive market. The first vehicle that set a speed record exceeding 100 km/h was the “La Jamais Contente,” an EV driven by Camille Jenatzy, a Belgian race driver and vehicle constructor. At the time, Oldsmobile, since 1908 part of General Motors, also manufactured EVs. EVs were easier to start and more comfortable, therefore being the early luxury vehicles: inter alia, Thomas A. Edison and Clara Ford owned EVs. In 1911, Charles F. Kettering, the founder and head of the GM R&D organi- zation from 1920 to 1947, invented the electric starter for ICEs. Because of this seminal breakthrough, which had first been applied in a Cadillac vehicle, the ICE-driven vehicles (fueled by the more easily available gasoline, as well as providing greater range) started to dominate the automotive markets globally. In the 1930s, the last American company building electric road vehicles stopped production. It took until 1964 when General Motors Research & Development integrated a silver–zinc battery originating from the US space program and electric motors in a Corvair-based EV, the Electrovair (see Figure 8.2(a)). In 1966, GM R&D developed the GM Electrovan (Figure 8.2(b)), the world’s first fuel cell vehicle, with an alkaline fuel cell Chapter 8 • The Voltec System—Energy Storage and Electric Propulsion 153 FIGURE 8.1 (a) Oldsmobile electric vehicle; (b) GMC electric truck. converting liquid oxygen and liquid hydrogen into electric energy. To drive the wheels, an AC induction motor was used. In 1969, General Motors presented a further experimental car, the XP-883. This concept vehicle combined a two-door hatchback body style with a two-cylinder opposed water-cooled engine, lead–acid batteries, a flywheel alternator and a DC series-wound electric motor. The XP-883 became an ancestor of a vehicle concept today known as plug-in hybrid EV. GM was also involved via its subsidiary Delco Electronics (cofounded by Kettering) into the design, development and testing of the Lunar Roving Vehicle which featured electric wheel hub motors and two 36-volt silver- zinc batteries. Three of these vehicles were operated on the moon by NASA astronauts within the framework of Apollo missions 15, 16 and 17. 154 LITHIUM-ION BATTERIES: ADVANCES AND APPLICATIONS FIGURE 8.2 (a) Electrovair (1964); (b) GM Electrovan (1966). (For color version of this figure, the reader is referred to the online version of this book.) But since all these technology strains were not mature enough for commercial application at that time, they fell into oblivion. In 1987, the first “World Solar Challenge”, a solar-powered car race